1. Field of the Invention
This invention is in the field of motor vehicle trailer hitches of the type having a receiver tube and a drawbar.
2. Description of Prior Art
Trailers are towed behind motor vehicles via a releasable coupling between the trailer and the vehicle. A common type of trailer hitch has a square tube mounted centrally beneath the rear bumper of the vehicle, oriented longitudinally, and open at the back. This is called a hitch receiver tube. A square drawbar is inserted into this tube and locked into it with a pin that passes completely through the tube and the drawbar. The back end of the pin is bent to stop the pin against the receiver tube, and the front end of the pin has a hole to receive a safety retainer such as a spring clip or pad lock. Another locking method is to provide internal threads in the drawbar aligned with the locking pin holes in the receiver tube. A bolt is threaded transversely into the drawbar from outside the receiver tube, and tightened to pull the drawbar against the inner wall of the receiver tube, eliminating play. The bolt may pass completely through the receiver tube and drawbar, exit the opposite side of the receiver tube, and have a lock nut or a transverse hole for a locking clip.
The back end of the drawbar can support any type of coupling mechanism, such as a ball for a trailer socket. The bar can also directly support a bicycle rack behind the vehicle. The present invention improves the convenience, speed, and safety of connecting and disconnecting the drawbar to the receiver tube.
The objective of the present invention is a trailer hitch drawbar that can be quickly inserted and locked into a trailer hitch receiver tube with a positive connection without play, which can be quickly released and removed.
This objective is achieved with a trailer hitch drawbar 1 having a cam bar 4 mounted along one side such that rotating the cam bar extends or retracts the side of the cam bar 4a along the side of the drawbar. This cam action firmly wedges the drawbar inside a receiver tube 9. An adjustment set screw 2 is provided to set the cam for optimum expansion force in a given receiver tube. A locking pin 5 extends from the drawbar when the cam bar is rotated to the lock position. The locking pin is operated by a second cam surface 4b on the cam bar moving against the inner end of the locking pin. The pin extends into the standard locking pin hole 11 in the receiver tube to prevent longitudinal slippage of the drawbar in the receiver tube. An adjustable drawbar stop 13 sets the penetration depth of the drawbar into the receiver tube to align the locking pin with the locking hole in the receiver tube. This allows instant insertion and locking of the drawbar without searching for pin alignment. The combination of the cam bar and locking pin results in a positive connection of the drawbar in the receiver tube without play, and one that can be quickly released.